I'm Kelvin Wachira Mwangi, a Senior Frontend Engineer with 10+ years of experience architecting high-performance, data-dense UIs for fintech and e-commerce platforms. I excel at leading teams, driving architectural decisions, and delivering measurable business impact by adopting modern frontend technologies like React and Next.js, and by building scalable design systems that unify experiences across web and mobile. I have a track record of improving user engagement and reducing build times through thoughtful architecture and rigorous process improvement. My specialty is migrating legacy systems to scalable micro-frontend architectures, mentoring engineers, and partnering with product and design to ship features on time while improving performance and user experience. Based in Nairobi, Kenya, I thrive in fast-paced environments and enjoy collaborating with cross-functional teams to translate complex requirements into robust, user-friendly interfaces.…

Kelvin Wachira Mwangi

I'm Kelvin Wachira Mwangi, a Senior Frontend Engineer with 10+ years of experience architecting high-performance, data-dense UIs for fintech and e-commerce platforms. I excel at leading teams, driving architectural decisions, and delivering measurable business impact by adopting modern frontend technologies like React and Next.js, and by building scalable design systems that unify experiences across web and mobile. I have a track record of improving user engagement and reducing build times through thoughtful architecture and rigorous process improvement. My specialty is migrating legacy systems to scalable micro-frontend architectures, mentoring engineers, and partnering with product and design to ship features on time while improving performance and user experience. Based in Nairobi, Kenya, I thrive in fast-paced environments and enjoy collaborating with cross-functional teams to translate complex requirements into robust, user-friendly interfaces.…

Available to hire

I’m Kelvin Wachira Mwangi, a Senior Frontend Engineer with 10+ years of experience architecting high-performance, data-dense UIs for fintech and e-commerce platforms. I excel at leading teams, driving architectural decisions, and delivering measurable business impact by adopting modern frontend technologies like React and Next.js, and by building scalable design systems that unify experiences across web and mobile. I have a track record of improving user engagement and reducing build times through thoughtful architecture and rigorous process improvement.

My specialty is migrating legacy systems to scalable micro-frontend architectures, mentoring engineers, and partnering with product and design to ship features on time while improving performance and user experience. Based in Nairobi, Kenya, I thrive in fast-paced environments and enjoy collaborating with cross-functional teams to translate complex requirements into robust, user-friendly interfaces.

See more

Skills

Experience Level

React JS
Expert
CSS
Expert
HTML5
Expert
JavaScript
Expert
TypeScript
Expert
GitHub
Expert
Node.js
Expert
GraphQL
Expert
Docker
Expert
Figma
Expert
Tailwind
Expert
GitHub CoPilot
Intermediate
See more

Language

English
Advanced

Work Experience

Principal Frontend Engineer at Ogilvy Africa
January 1, 2023 - Present
Led and mentored a team of 5 frontend engineers building the Optimus CRM platform; established a rigorous code review process that improved quality and velocity. Spearheaded a migration to a scalable microservices architecture using NestJS and Postgres, enhancing modularity and deployment independence. Architected and implemented a comprehensive UI framework and design system across web and mobile, which boosted user engagement by 15%.
Frontend Engineer Lead at WPP Scangroup
December 31, 2022 - September 3, 2025
Led frontend development for major e-commerce and fintech projects emphasizing performance, scalability, and UX. Architected a Next.js patient-facing application improving load time by 25% and SEO. Led frontend development for Naivas Online, enhancing retail customer experience. Re-architected legacy Webpack setup to reduce build times by 10% and improve developer efficiency. Contributed to the frontend of M-Pesa, focusing on seamless and secure experience for 60 million users.
Frontend Engineer Lead at Centuria
April 30, 2017 - September 3, 2025
Directed frontend strategy for internal business applications with modern JavaScript frameworks. Led migration of two key apps (Sentinel, Kodi) from Vaadin to React, resulting in a 40% bug report reduction and 15% higher user retention. Led UI/UX redesign for Sentinel, improving user satisfaction by 10%. Pioneered Play-Scala adoption for backend, improving stability and collaboration.
Principal Frontend Engineer at OGILVY AFRICA
January 1, 2023 - November 6, 2025
Led and mentored a team of 5 frontend engineers on the Optimus CRM platform; instituted a rigorous code-review process that improved code quality and velocity, ensuring on-time delivery of major features in 2023. Spearheaded migration of the Optimus core application to a scalable microservices architecture using NestJS and Postgres. Architected and implemented a comprehensive UI framework and design system for Optimus, standardizing components across web and mobile and boosting user engagement by 15%.
Frontend Engineer Lead at WPP SCANGROUP
December 1, 2022 - December 1, 2022
Led frontend development for major e-commerce and fintech projects with focus on performance, scalability, and user experience. Ponea Health: Next.js SSR improved initial page load by 25% and contributed to SEO rankings. Naivas Online: Led frontend development for Eastern Africa's largest retailer, delivering an intuitive, responsive online store. Firsti E-commerce: Re-architected legacy Webpack configuration; implemented advanced caching and tree-shaking that reduced production build times by 10% and improved developer workflow. M-Pesa: Contributed to frontend development for Africa's largest fintech platform serving 60+ million users.
Frontend Engineer Lead at CENTURIA
April 1, 2017 - April 1, 2017
Directed frontend strategy and execution for internal business applications, migrating two critical apps (Sentinel, Kodi) from Vaadin to React; this reduced the bug report queue by 40% and improved performance, leading to a 15% increase in user retention. Led UI/UX redesign for the Sentinel facility tracking application, improving user satisfaction. Pioneered the Play-Scala backend framework adoption for improved stability and developer collaboration.

Education

Diploma in Graphic Design and Web Development at Nairobits School of Design
January 1, 2012 - December 31, 2012
Diploma at NAIROBITS SCHOOL OF DESIGN
January 1, 2012 - January 1, 2012

Qualifications

Add your qualifications or awards here.

Industry Experience

Financial Services, Retail, Software & Internet, Healthcare, Telecommunications, Wholesale & Distribution, Media & Entertainment, Professional Services
    paper Sentinel – Modernizing Facility Management

    The Problem: An internal facility tracking application was built on an outdated Vaadin framework, resulting in poor performance, high maintenance costs, and low user adoption.

    The Solution: As the lead frontend developer, I spearheaded the complete migration of the Sentinel application to a modern, maintainable, and performant React-based architecture.

    The Outcome: The migration significantly improved the user experience and system stability, leading to a 10% increase in user satisfaction and a 15% increase in user retention.

    My Role & Contributions:

    Led the UI/UX design thinking process with stakeholders, translating business needs into an intuitive and efficient user interface.

    Developed a new, robust frontend architecture using React, enabling seamless integration with the existing Scala backend systems.

    The successful migration and redesign directly addressed user pain points, increasing operational efficiency by 20% and reducing system response times by 35%.

    Tech Stack: React, JavaScript, Semantic-UI, Scala

    paper Ponea Health – Revolutionizing Healthcare Access

    The Problem: Healthcare accessibility in Kenya was severely limited by geographic and logistical barriers, making it difficult for patients to connect with qualified medical providers in a timely manner.

    The Solution: As a lead frontend engineer, I was responsible for architecting and building a user-friendly web platform that connected patients with vetted providers via a powerful search interface and secure virtual consultations.

    The Outcome: The platform successfully launched and now serves thousands of users, demonstrably improving access to quality healthcare services across the country.

    My Role & Contributions:

    Architected the primary patient-facing application using Next.js for server-side rendering, which improved initial page load performance by 25% and contributed to higher SEO rankings.

    Integrated the Algolia search API to build a highly responsive and typo-tolerant provider search experience, a core feature that led to a 30% increase in successful appointment bookings within the first quarter post-launch.

    Implemented the Sendbird Calls API to enable secure, real-time video consultations directly within the browser, expanding healthcare accessibility to remote users.

    Tech Stack: Next.js, React, MUI, Algolia, Sendbird Calls

    paper Optimus – Unified Customer Lifecycle Management

    The Problem: Businesses lacked a single, cohesive platform to manage the entire customer journey, from lead generation and marketing automation to sales and long-term advocacy.

    The Solution: I led a team of five engineers in the design and development of Optimus, a comprehensive web and mobile CRM platform. My focus was on creating a seamless, data-dense user experience and a scalable underlying architecture.

    The Outcome: The platform streamlined client workflows and, following the launch of a redesigned mobile companion app and a new UI framework, boosted user engagement by 15%.

    My Role & Contributions:

    Led the migration of the platform’s core to a NestJS and Postgres-based microservices architecture, enhancing scalability and developer independence.

    Designed and implemented a comprehensive design system and UI framework that ensured brand consistency and high-quality code across all modules.

    Developed a dedicated mobile app companion that significantly improved the user experience for on-the-go lead management and customer interaction.